Recent concern for the welfare of the world population has included consideration of additional means for feeding the rapidly increasing number of people involved. The problem embraces providing both adequate per capita caloric intake and a balanced diet, with particular reference to the lack of protein affording foods in many parts of the world. One means for providing necessary protein supplies is through the growth of fungal mycelia for use either as food or food supplements.
Production of edible fungal mycelia in large quantities may be accomplished by fermentation processes employing a carbohydrate substrate. The principal requirements are that the substrate material be relatively inexpensive and readily consumed by the selected microorganism.
The human metabolic system produces uric acid in the metabolism of ribonucleic acid. Since man does not have a uricase enzyme system, uric acid is not further broken down and is excreted in the urine. Because uric acid salts have a very low solubility in biological fluids, they will accumulate in the body in crystalline form if produced in larger quantities than the body can excrete. This may lead to the condition known as gout. For this reason nutritionists recommend that the ribonucleic acid intake in diet be kept at a low level.
Fungal mycelia generally contain from 7 to 9% nucleic acids. If the fungal mycelia are to be used as a protein source in human feeding, nutritionists generally recommend that the amount of nucleic acids contributed by single cell protein or fungal mycelia should not exceed 2 grams per day.
A preferrred way of utilizing edible fungal mycelia is in the form of whole cells. Accordingly, there is a need for a means for removing nucleic acids from within the fungal mycelia. This desirably is accomplished with a minimum loss of protein material from within the cells in order to maintain the nutritional attractiveness of such fungal mycelia. One method found to work well with some fungi in reducing nucleic acid content is the isothermal shock method disclosed in U.S. Pat. No. 4,041,189 Any procedure permitting increased effectiveness of this procedure should therefore decrease the possibility of gout when processed fungal material is used as human food.